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Gu Y, Wang Y, Liu M, Lu HM, Yang Y. Development of an algorithm for proton dose calculation in magnetic fields. Med Phys 2024. [PMID: 38922910 DOI: 10.1002/mp.17262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 05/27/2024] [Accepted: 06/01/2024] [Indexed: 06/28/2024] Open
Abstract
BACKGROUND The advantages of proton therapy can be further enhanced with online magnetic resonance imaging (MRI) guidance. One of the challenges in the realization of MRI-guided proton therapy (MRPT) is accurately calculating the radiation dose in the presence of magnetic fields. PURPOSE This study aims to develop an efficient and accurate proton dose calculation algorithm adapted to the presence of magnetic fields. METHODS An analytical-numerical radiation dose calculation algorithm, Proton and Ion Dose Engine (PRIDE), was developed. The algorithm combines the pencil beam algorithm (PBA) with a novel iterative voxel-based ray-tracing algorithm. The new ray-tracing method uses fewer assumptions and ensures broader applicability for proton beam trajectory prediction in magnetic fields, and has been compared to Wolf's method and Schellhammer's method. The accuracy of PRIDE algorithm was validated on three phantoms and two practical plans (one single-field water plan and one prostate tumor plan) in different magnetic field strengths up to 3.0 T. The validation was performed by comparing the results against the Monte Carlo (MC) simulations, using the global gamma index criteria of 2%/2 mm and 3%/3 mm with a 10% threshold. RESULTS PRIDE showed good agreement with MC in homogeneous and slab heterogeneous phantom, achieving gamma passing rates (%GPs) above 99% for 2%/2 mm criteria when magnetic field strength is not greater than 1.5 T. Although the agreement decreased for scenarios involving high proton energy (240 MeV) and strong magnetic field (3.0 T), the 2%/2 mm %GPs still remained above 98%. In lateral heterogeneous phantom, the accuracy of PRIDE decreased due to the PBA's limitation. For the two practical plans in different magnetic fields, %GPs exceeded 98% and 99% for 2%/2 mm and 3%/3 mm criteria, respectively. CONCLUSIONS PRIDE can perform efficient and accurate proton dose calculation in magnetic fields up to 3.0 T, and is expected to work as a useful tool for proton dose calculation in MRPT.
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Affiliation(s)
- Yue Gu
- Department of Engineering and Applied Physics, University of Science and Technology of China, Hefei, Anhui, China
| | - Yuxiang Wang
- Department of Engineering and Applied Physics, University of Science and Technology of China, Hefei, Anhui, China
- Hefei Ion Medical Center, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China
| | - Meiqi Liu
- Department of Engineering and Applied Physics, University of Science and Technology of China, Hefei, Anhui, China
| | - Hsiao-Ming Lu
- Hefei Ion Medical Center, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China
- Ion Medical Research Institute, University of Science and Technology of China, Hefei, Anhui, China
| | - Yidong Yang
- Department of Engineering and Applied Physics, University of Science and Technology of China, Hefei, Anhui, China
- Ion Medical Research Institute, University of Science and Technology of China, Hefei, Anhui, China
- Department of Radiation Oncology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China
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Duetschler A, Safai S, Weber DC, Lomax AJ, Zhang Y. The impact of motion on onboard MRI-guided pencil beam scanned proton therapy treatments. Phys Med Biol 2024; 69:095003. [PMID: 38537287 DOI: 10.1088/1361-6560/ad3885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 03/26/2024] [Indexed: 04/16/2024]
Abstract
Objective.Online magnetic resonance imaging (MRI) guidance could be especially beneficial for pencil beam scanned (PBS) proton therapy of tumours affected by respiratory motion. For the first time to our knowledge, we investigate the dosimetric impact of respiratory motion on MRI-guided proton therapy compared to the scenario without magnetic field.Approach.A previously developed analytical proton dose calculation algorithm accounting for perpendicular magnetic fields was extended to enable 4D dose calculations. For two geometrical phantoms and three liver and two lung patient cases, static treatment plans were optimised with and without magnetic field (0, 0.5 and 1.5 T). Furthermore, plans were optimised using gantry angle corrections (0.5 T +5° and 1.5 T +15°) to reproduce similar beam trajectories compared to the 0 T reference plans. The effect of motion was then considered using 4D dose calculations without any motion mitigation and simulating 8-times volumetric rescanning, with motion for the patient cases provided by 4DCT(MRI) data sets. Each 4D dose calculation was performed for different starting phases and the CTV dose coverageV95%and homogeneityD5%-D95%were analysed.Main results.For the geometrical phantoms with rigid motion perpendicular to the beam and parallel to the magnetic field, a comparable dosimetric effect was observed independent of the magnetic field. Also for the five 4DCT(MRI) cases, the influence of motion was comparable for all magnetic field strengths with and without gantry angle correction. On average, the motion-induced decrease in CTVV95%from the static plan was 17.0% and 18.9% for 1.5 T and 0.5 T, respectively, and 19.9% without magnetic field.Significance.For the first time, this study investigates the combined impact of magnetic fields and respiratory motion on MR-guided proton therapy. The comparable dosimetric effects irrespective of magnetic field strength indicate that the effects of motion for future MR-guided proton therapy may not be worse than for conventional PBS proton therapy.
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Affiliation(s)
- Alisha Duetschler
- Center for Proton Therapy, Paul Scherrer Institute, 5232 Villigen PSI, CH, Switzerland
- Department of Physics, ETH Zürich, 8092 Zürich, CH, Switzerland
| | - Sairos Safai
- Center for Proton Therapy, Paul Scherrer Institute, 5232 Villigen PSI, CH, Switzerland
| | - Damien C Weber
- Center for Proton Therapy, Paul Scherrer Institute, 5232 Villigen PSI, CH, Switzerland
- Department of Radiation Oncology, University Hospital of Zürich, 8091 Zürich, CH, Switzerland
- Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, 3010 Bern, CH, Switzerland
| | - Antony J Lomax
- Center for Proton Therapy, Paul Scherrer Institute, 5232 Villigen PSI, CH, Switzerland
- Department of Physics, ETH Zürich, 8092 Zürich, CH, Switzerland
| | - Ye Zhang
- Center for Proton Therapy, Paul Scherrer Institute, 5232 Villigen PSI, CH, Switzerland
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Blum I, Wong JS, Godino Padre K, Stolzenberg J, Fuchs H, Baumann KS, Poppe B, Looe HK. Fano cavity test and investigation of the response of the Roos chamber irradiated by proton beams in perpendicular magnetic fields up to 1 T. Phys Med Biol 2024; 69:085021. [PMID: 38452383 DOI: 10.1088/1361-6560/ad311a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Accepted: 03/07/2024] [Indexed: 03/09/2024]
Abstract
Objective. The aim of this work is to investigate the response of the Roos chamber (type 34001) irradiated by clinical proton beams in magnetic fields.Approach. At first, a Fano test was implemented in Monte Carlo software package GATE version 9.2 (based on Geant4 version 11.0.2) using a cylindrical slab geometry in a magnetic field up to 1 T. In accordance to an experimental setup (Fuchset al2021), the magnetic field correction factorskQB⃗of the Roos chamber were determined at different energies up to 252 MeV and magnetic field strengths up to 1 T, by separately simulating the ratios of chamber signalsMQ/MQB⃗,without and with magnetic field, and the dose-conversion factorsDw,QB⃗/Dw,Qin a small cylinder of water, with and without magnetic field. Additionally, detailed simulations were carried out to understand the observed magnetic field dependence.Main results. The Fano test was passed with deviations smaller than 0.25% between 0 and 1 T. The ratios of the chamber signals show both energy and magnetic field dependence. The maximum deviation of the dose-conversion factors from unity of 0.22% was observed at the lowest investigated proton energy of 97.4 MeV andB⃗= 1 T. The resultingkQB⃗factors increase initially with the applied magnetic field and decrease again after reaching a maximum at around 0.5 T; except for the lowest 97.4 MeV beam that show no observable magnetic field dependence. The deviation from unity of the factors is also larger for higher proton energies, where the maximum lies at 1.0035(5), 1.0054(7) and 1.0069(7) for initial energies ofE0= 152, 223.4 and 252 MeV, respectively.Significance. Detailed Monte Carlo studies showed that the observed effect can be mainly attributed to the differences in the transport of electrons produced both outside and inside of the air cavity in the presence of a magnetic field.
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Affiliation(s)
- Isabel Blum
- University Clinic for Medical Radiation Physics, Medical Campus Pius Hospital, Carl von Ossietzky University, Oldenburg, Germany
| | - Jing Syuen Wong
- University Clinic for Medical Radiation Physics, Medical Campus Pius Hospital, Carl von Ossietzky University, Oldenburg, Germany
| | - Krishna Godino Padre
- University Clinic for Medical Radiation Physics, Medical Campus Pius Hospital, Carl von Ossietzky University, Oldenburg, Germany
| | - Jessica Stolzenberg
- University Clinic for Medical Radiation Physics, Medical Campus Pius Hospital, Carl von Ossietzky University, Oldenburg, Germany
| | - Hermann Fuchs
- Division of Medical Physics, Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Kilian-Simon Baumann
- University Hospital Giessen-Marburg, Department of Radiotherapy and Radiooncology, Marburg, Germany
- University of Applied Sciences, Institute of Medical Physics and Radiation Protection, Giessen, Germany
- Marburg Ion-Beam Therapy Center, Marburg, Germany
| | - Björn Poppe
- University Clinic for Medical Radiation Physics, Medical Campus Pius Hospital, Carl von Ossietzky University, Oldenburg, Germany
| | - Hui Khee Looe
- University Clinic for Medical Radiation Physics, Medical Campus Pius Hospital, Carl von Ossietzky University, Oldenburg, Germany
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Gebauer B, Baumann KS, Fuchs H, Georg D, Oborn BM, Looe HK, Lühr A. Proton dosimetry in a magnetic field: Measurement and calculation of magnetic field correction factors for a plane-parallel ionization chamber. Med Phys 2024; 51:2293-2305. [PMID: 37898105 DOI: 10.1002/mp.16797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 08/31/2023] [Accepted: 09/04/2023] [Indexed: 10/30/2023] Open
Abstract
BACKGROUND The combination of magnetic resonance imaging and proton therapy offers the potential to improve cancer treatment. The magnetic field (MF)-dependent change in the dosage of ionization chambers in magnetic resonance imaging-integrated proton therapy (MRiPT) is considered by the correction factork B ⃗ , M , Q $k_{\vec{B},M,Q}$ , which needs to be determined experimentally or computed via Monte Carlo (MC) simulations. PURPOSE In this study,k B ⃗ , M , Q $k_{\vec{B},M,Q}$ was both measured and simulated with high accuracy for a plane-parallel ionization chamber at different clinical relevant proton energies and MF strengths. MATERIAL AND METHODS The dose-response of the Advanced Markus chamber (TM34045, PTW, Freiburg, Germany) irradiated with homogeneous 10 × $\times$ 10 cm2 $^2$ quasi mono-energetic fields, using 103.3, 128.4, 153.1, 223.1, and 252.7 MeV proton beams was measured in a water phantom placed in the MF of an electromagnet with MF strengths of 0.32, 0.5, and 1 T. The detector was positioned at a depth of 2 g/cm2 $^2$ in water, with chamber electrodes parallel to the MF lines and perpendicular to the proton beam incidence direction. The measurements were compared with TOPAS MC simulations utilizing COMSOL-calculated 0.32, 0.5, and 1 T MF maps of the electromagnet.k B ⃗ , M , Q $k_{\vec{B},M,Q}$ was calculated for the measurements for all energies and MF strengths based on the equation:k B ⃗ , M , Q = M Q M Q B ⃗ $k_{\vec{B},M,Q}=\frac{M_\mathrm{Q}}{M_\mathrm{Q}^{\vec{B}}}$ , whereM Q B ⃗ $M_\mathrm{Q}^{\vec{B}}$ andM Q $M_\mathrm{Q}$ were the temperature and air-pressure corrected detector readings with and without the MF, respectively. MC-based correction factors were determined ask B ⃗ , M , Q = D det D det B ⃗ $k_{\vec{B},M,Q}=\frac{D_\mathrm{det}}{D_\mathrm{det}^{\vec{B}}}$ , whereD det B ⃗ $D_\mathrm{det}^{\vec{B}}$ andD det $D_\mathrm{det}$ were the doses deposited in the air cavity of the ionization chamber model with and without the MF, respectively. Furthermore, MF effects on the chamber dosimetry are studied using MC simulations, examining the impact on the absorbed dose-to-water (D W $D_{W}$ ) and the shift in depth of the Bragg peak. RESULTS The detector showed a reduced dose-response for all measured energies and MF strengths, resulting in experimentally determinedk B ⃗ , M , Q $k_{\vec{B},M,Q}$ values larger than unity. For all energies and MF strengths examined,k B ⃗ , M , Q $k_{\vec{B},M,Q}$ ranged between 1.0065 and 1.0205. The dependence on the energy and the MF strength was found to be non-linear with a maximum at 1 T and 252.7 MeV. The MC simulatedk B ⃗ , M , Q $k_{\vec{B},M,Q}$ values agreed with the experimentally determined correction factors within their standard deviations with a maximum difference of 0.6%. The MC calculated impact onD W $D_{W}$ was smaller 0.2 %. CONCLUSION For the first time, measurements and simulations were compared for proton dosimetry within MFs using an Advanced Markus chamber. Good agreement ofk B ⃗ , M , Q $k_{\vec{B},M,Q}$ was found between experimentally determined and MC calculated values. The performed benchmarking of the MC code allows for calculatingk B ⃗ , M , Q $k_{\vec{B},M,Q}$ for various ionization chamber models, MF strengths and proton energies to generate the data needed for a proton dosimetry protocol within MFs and is, therefore, a step towards MRiPT.
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Affiliation(s)
- Benjamin Gebauer
- OncoRay National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
- Institute of Radiooncology-OncoRay, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
| | - Kilian-Simon Baumann
- Department of Radiotherapy and Radiooncology, University Medical Center Giessen-Marburg, Marburg, Germany
- University of Applied Sciences, Institute of Medical Physics and Radiation Protection, Giessen, Germany
- Ion-Beam Therapy Center, Marburg, Germany
| | - Hermann Fuchs
- Department of Radiation Oncology, Medical University of Vienna, Wien, Austria
- MedAustron Iontherapy centre, Wiener Neustadt, Austria
| | - Dietmar Georg
- Department of Radiation Oncology, Medical University of Vienna, Wien, Austria
- MedAustron Iontherapy centre, Wiener Neustadt, Austria
| | - Brad M Oborn
- Institute of Radiooncology-OncoRay, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, New South Wales, Australia
- Illawarra Cancer Care Centre, Wollongong, New South Wales, Australia
| | - Hui-Khee Looe
- Department for Radiotherapy and Radiooncology, Pius Hospital, Medical Campus Carl von Ossietzky University, Oldenburg, Germany
| | - Armin Lühr
- Department of Physics, TU Dortmund University, Dortmund, Germany
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Asadi A, Akhavanallaf A, Hosseini SA, Vosoughi N, Zaidi H. Development and validation of an optimal GATE model for proton pencil-beam scanning delivery. Z Med Phys 2023; 33:591-600. [PMID: 36424313 PMCID: PMC10751712 DOI: 10.1016/j.zemedi.2022.10.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 10/14/2022] [Accepted: 10/14/2022] [Indexed: 11/23/2022]
Abstract
OBJECTIVE To develop and validate a versatile Monte Carlo (MC)-based dose calculation engine to support MC-based dose verification of treatment planning systems (TPSs) and quality assurance (QA) workflows in proton therapy. METHODS The GATE MC toolkit was used to simulate a fixed horizontal active scan-based proton beam delivery (SIEMENS IONTRIS). Within the nozzle, two primary and secondary dose monitors have been designed to enable the comparison of the accuracy of dose estimation from MC simulations with respect to physical QA measurements. The developed beam model was validated against a series of commissioning measurements using pinpoint chambers and 2D array ionization chambers (IC) in terms of lateral profiles and depth dose distributions. Furthermore, beam delivery module and treatment planning has been validated against the literature deploying various clinical test cases of the AAPM TG-119 (c-shape phantom) and a prostate patient. RESULTS MC simulations showed excellent agreement with measurements in the lateral depth-dose parameters and spread-out Bragg peak (SOBP) characteristics within a maximum relative error of 0.95 mm in range, 1.83% in entrance to peak ratio, 0.27% in mean point-to-point dose difference, and 0.32% in peak location. The mean relative absolute difference between MC simulations and measurements in terms of absorbed dose in the SOBP region was 0.93% ± 0.88%. Clinical phantom studies showed a good agreement compared to research TPS (relative error for TG-119 planning target volume PTV-D95 ∼ 1.8%; and for prostate PTV-D95 ∼ -0.6%). CONCLUSION We successfully developed a MC model for the pencil beam scanning system, which appears reliable for dose verification of the TPS in combination with QA information, prior to patient treatment.
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Affiliation(s)
- Ali Asadi
- Department of Energy Engineering, Sharif University of Technology, Tehran, Iran
| | - Azadeh Akhavanallaf
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva, Switzerland
| | | | - Naser Vosoughi
- Department of Energy Engineering, Sharif University of Technology, Tehran, Iran
| | - Habib Zaidi
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva, Switzerland; Geneva University Neurocenter, Geneva University, Geneva, Switzerland; Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; Department of Nuclear Medicine, University of Southern Denmark, Odense, Denmark.
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6
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Fuchs H, Padilla-Cabal F, Oborn BM, Georg D. Commissioning a beam line for MR-guided particle therapy assisted by in silico methods. Med Phys 2023; 50:1019-1028. [PMID: 36504399 DOI: 10.1002/mp.16143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 10/11/2022] [Accepted: 11/16/2022] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Radiation therapy is continuously moving towards more precise dose delivery. The combination of online MR imaging and particle therapy, for example, radiation therapy using protons or carbon ions, could enable the next level of precision in radiotherapy. In particle therapy, research towards a combination of MR and particle therapy is well underway, but still far from clinical systems. The combination of high magnetic fields with particle therapy delivery poses several challenges for treatment planning, treatment workflow, dose delivery, and dosimetry. PURPOSE To present a workflow for commissioning of a light ion beam line with an integrated dipole magnet to perform MR-guided particle therapy (MRgPT) research, producing not only basic beam data but also magnetic field maps for accurate dose calculation. Accurate dose calculation in magnetic field environments requires high-quality magnetic field maps to compensate for magnetic-field-dependent trajectory changes and dose perturbations. METHODS The research beam line at MedAustron was coupled with a resistive dipole magnet positioned at the isocenter. Beam data were measured for proton and carbon ions with and without an applied magnetic field of 1 T. Laterally integrated depth-dose curves (IDC) as well as beam profiles were measured in water while beam trajectories were measured in air. Based on manufacturer data, an in silico model of the magnet was created, allowing to extract high-quality 3D magnetic field data. An existing GATE/Geant4 Monte Carlo (MC) model of the beam line was extended with the generated magnetic field data and benchmarked against experimental data. RESULTS A 3D magnetic field volume covering fringe fields until 50 mT was found to be sufficient for an accurate beam trajectory modeling. The effect on particle range retraction was found to be 2.3 and 0.3 mm for protons and carbon ions, respectively. Measured lateral beam offsets in water agreed within 0.4 and -0.5 mm with MC simulations for protons and carbon ions, respectively. Experimentally determined in-air beam trajectories agreed within 0.4 mm in the homogeneous magnetic field area. CONCLUSION The presented approach based on in silico modeling and measurements allows to commission a beam line for MRgPT while providing benchmarking data for the magnetic field modeling, required for state-of-the art dose calculation methods.
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Affiliation(s)
- Hermann Fuchs
- Division of Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna, Wien, Austria.,MedAustron Ion Therapy Center, Wiener Neustadt, Austria
| | - Fatima Padilla-Cabal
- Division of Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Bradley M Oborn
- Institute of Radiooncology-OncoRay, Radiooncology, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany.,Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia.,Illawarra Cancer Care Centre, Wollongong Hospital, Wollongong, NSW, Australia
| | - Dietmar Georg
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria.,Division of Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
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Kerschbaum-Gruber S, Padilla-Cabal F, Mara E, Lohberger B, Georg D, Fuchs H. An external perpendicular magnetic field does not influence survival and DNA damage after proton and carbon ion irradiation in human cancer cells. Z Med Phys 2022; 32:326-333. [PMID: 35058110 PMCID: PMC9948843 DOI: 10.1016/j.zemedi.2021.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 10/15/2021] [Accepted: 11/05/2021] [Indexed: 11/17/2022]
Abstract
BACKGROUND AND PURPOSE Magnetic field effects on the radiobiological effectiveness during treatment of magnetic resonance (MRI) guided particle therapy are being debated. This study aims at assessing the influence of a perpendicular magnetic field on the biological effects in two human cancer cell lines irradiated with proton or carbon ions. METHODS AND MATERIALS In vitro cell irradiations were performed in water inside a perpendicular magnetic field of 0 and 1T for both protons and carbon ions. Samples were located in the center of a spread-out Bragg peak at 8cm water equivalent depth with a dose averaged linear energy transfer (LETd) of 4.2 or 83.4keV/μm for protons and carbon ions, respectively. Physical dose levels of 0, 0.5, 1, 2, 4 and 6Gy were employed. The irradiation field was shifted and laterally enlarged, to compensate for the beam deflection due to the magnetic field and ensure consistent and homogenous irradiations of the flasks. The human cancer cell lines SKMel (Melanoma) and SW1353 (chondrosarcoma) were selected which represent a high and a low (α/β)x ratio cell type. Cell survival curves were generated applying a linear-quadratic curve fit. DNA damage and DNA damage clearance were assessed via γH2AX foci quantification at 1 and 24h post radiation treatment. RESULTS Without a magnetic field, RBE10 values of 1.04±0.03 (SW1353) and 1.51±0.06 (SKMel) as well as RBE80 values of 0.93±0.15 (SW1353) and 2.28±0.40 (SKMel) were calculated for protons. Carbon treatments yielded RBE10 values of 1.68±0.04 (SW1353) and 2.30±0.07 (SKMel) and RBE80 values of 2.19±0.24 (SW1353) and 4.06±0.33 (SKMel). For a field strength of B=1T, RBE10 values of 1.06±0.03 (SW1353) and 1.47±0.06 (SKMel) resulted from protons, while RBE10 values of 1.70±0.05 (SW1353) and 2.37±0.08 (SKMel) were obtained for carbon ions. RBE80 values were calculated to be 1.06±0.12 (SW1353) and 2.33±0.40 (SKMel) following protons and 2.13±0.25 (SW1353) and 4.29±0.35 (SKMel) following carbon treatments. Substantially increased γH2AX foci per nucleus were found in both cell lines 1h after radiation with both ion species. At the 24h time point only carbon treated samples of both cell lines showed increased γH2AX levels. The presence of the magnetic field did neither influence the survival parameters of either cell line, nor initial DNA damage and DNA damage clearance. CONCLUSIONS Applying a perpendicular magnetic field did not influence the cell survival, DNA repair, nor the biological effectiveness of protons or carbon ions in two human cancer cell lines.
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Affiliation(s)
- Sylvia Kerschbaum-Gruber
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria; MedAustron Ion Therapy Center, Wiener Neustadt, Austria
| | - Fatima Padilla-Cabal
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria; MedAustron Ion Therapy Center, Wiener Neustadt, Austria
| | | | - Birgit Lohberger
- Department of Orthopedics and Trauma, Medical University Graz, Graz, Austria
| | - Dietmar Georg
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria; MedAustron Ion Therapy Center, Wiener Neustadt, Austria
| | - Hermann Fuchs
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria; MedAustron Ion Therapy Center, Wiener Neustadt, Austria.
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Fujii Y, Ueda H, Umegaki K, Matsuura T. An initial systematic study of the linear energy transfer distributions of a proton beam under a transverse magnetic field. Med Phys 2022; 49:1839-1852. [DOI: 10.1002/mp.15478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 01/11/2022] [Accepted: 01/12/2022] [Indexed: 11/10/2022] Open
Affiliation(s)
- Yusuke Fujii
- Graduate School of Engineering Hokkaido University Sapporo Hokkaido Japan
- Hitachi Ltd. Hitachi Ibaraki Japan
| | - Hideaki Ueda
- Faculty of Engineering Hokkaido University Sapporo Hokkaido Japan
| | - Kikuo Umegaki
- Faculty of Engineering Hokkaido University Sapporo Hokkaido Japan
- Proton Beam Therapy Center Hokkaido University Hospital Sapporo Hokkaido Japan
- Department of Medical Physics Hokkaido University Hospital Sapporo Hokkaido Japan
| | - Taeko Matsuura
- Faculty of Engineering Hokkaido University Sapporo Hokkaido Japan
- Proton Beam Therapy Center Hokkaido University Hospital Sapporo Hokkaido Japan
- Department of Medical Physics Hokkaido University Hospital Sapporo Hokkaido Japan
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9
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Cavallone M, Prezado Y, De Marzi L. Converging Proton Minibeams with Magnetic Fields for Optimized Radiation Therapy: A Proof of Concept. Cancers (Basel) 2021; 14:cancers14010026. [PMID: 35008189 PMCID: PMC8750079 DOI: 10.3390/cancers14010026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 12/17/2021] [Accepted: 12/20/2021] [Indexed: 12/14/2022] Open
Abstract
Proton MiniBeam Radiation Therapy (pMBRT) is a novel strategy that combines the benefits of minibeam radiation therapy with the more precise ballistics of protons to further optimize the dose distribution and reduce radiation side effects. The aim of this study is to investigate possible strategies to couple pMBRT with dipole magnetic fields to generate a converging minibeam pattern and increase the center-to-center distance between minibeams. Magnetic field optimization was performed so as to obtain the same transverse dose profile at the Bragg peak position as in a reference configuration with no magnetic field. Monte Carlo simulations reproducing realistic pencil beam scanning settings were used to compute the dose in a water phantom. We analyzed different minibeam generation techniques, such as the use of a static multislit collimator or a dynamic aperture, and different magnetic field positions, i.e., before or within the water phantom. The best results were obtained using a dynamic aperture coupled with a magnetic field within the water phantom. For a center-to-center distance increase from 4 mm to 6 mm, we obtained an increase of peak-to-valley dose ratio and decrease of valley dose above 50%. The results indicate that magnetic fields can be effectively used to improve the spatial modulation at shallow depth for enhanced healthy tissue sparing.
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Affiliation(s)
- Marco Cavallone
- Centre de Protonthérapie d’Orsay, Department of Radiation Oncology, Institut Curie, Campus Universitaire, PSL Research University, 91898 Orsay, France
- Correspondence: (M.C.); (L.D.M.)
| | - Yolanda Prezado
- Institut Curie, Université PSL, CNRS UMR3347, Inserm U1021, Signalisation Radiobiologie et Cancer, 91400 Orsay, France;
| | - Ludovic De Marzi
- Centre de Protonthérapie d’Orsay, Department of Radiation Oncology, Institut Curie, Campus Universitaire, PSL Research University, 91898 Orsay, France
- Institut Curie, Campus Universitaire, PSL Research University, University Paris Saclay, INSERM LITO, 91898 Orsay, France
- Correspondence: (M.C.); (L.D.M.)
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Wang X, Pan H, Cheng Q, Wang X, Xu W. Dosimetric Deviations of Bragg-Peak Position Shifts in Uniform Magnetic Fields for Magnetic Resonance Imaging-Guiding Proton Radiotherapy: A Monte Carlo Study. Front Public Health 2021; 9:641915. [PMID: 34414150 PMCID: PMC8369236 DOI: 10.3389/fpubh.2021.641915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 06/02/2021] [Indexed: 11/15/2022] Open
Abstract
Objective: To investigate dosimetric deviations in scanning protons for Bragg-peak position shifts, which were caused by proton spiral tracks in an ideal uniform field of magnetic resonance (MRI) imaging-guided proton radiotherapy (MRI-IGPRT). Methods: The FLUKA Monte-Carlo (MC) code was used to simulate the spiral tracks of protons penetrating water with initial energies of 70–270 MeV under the influence of field strength of 0.0–3.0 Tesla in commercial MRI systems. Two indexes, lateral shift (marked as WD) perpendicular to the field and a penetration-depth shift (marked as ΔDD) along the beam path, were employed for the Bragg-peak position of spiral proton track analysis. A comparison was performed between MC and classical analytical model to check the simulation results. The shape of the 2D/3D dose distribution of proton spots at the depth of Bragg-Peak was also investigated. The ratio of Gaussian-fit value between longitudinal and transverse major axes was used to indicate the asymmetric index. The skewness of asymmetry was evaluated at various dose levels by the radius ratio of circumscribed and inscribed circles by fitting a semi-ellipse circle of 2D distribution. Results: The maximum of WD deflection is 2.82 cm while the maximum of shortening ΔDD is 0.44 cm for proton at 270 MeV/u under a magnetic field of 3.0 Tesla. The trend of WD and ΔDD from MC simulation was consistent with the analytical model, which means the reverse equation of the analytical model can be applied to determine the proper field strength of the magnet and the initial energy of the proton for the planned dose. The asymmetry of 2D/3D dose distribution under the influence of a magnetic field was increased with higher energy, and the skewness of asymmetry for one proton energy at various dose levels was also increased with a larger radius, i.e., a lower dose level. Conclusions: The trend of the spiral proton track under a uniform magnetic field was obtained in this study using either MC simulation or the analytical model, which can provide an optimized and planned dose of the proton beam in the clinical application of MRI-IGPRT.
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Affiliation(s)
- Xiaowa Wang
- Department of Nulcear Science and Technology, Institute of Modern Physics, Fudan University, Shanghai, China.,Key Laboratory of Nuclear Physics and Ion-Beam Application (MOE), Fudan University, Shanghai, China.,Shanghai Proton and Heavy Ion Center, Shanghai, China.,Shanghai Engineering Research Center of Proton and Heavy Ion Radiation Therapy, Shanghai, China
| | - Hailun Pan
- Department of Nulcear Science and Technology, Institute of Modern Physics, Fudan University, Shanghai, China.,Key Laboratory of Nuclear Physics and Ion-Beam Application (MOE), Fudan University, Shanghai, China
| | - Qinqin Cheng
- Department of Nulcear Science and Technology, Institute of Modern Physics, Fudan University, Shanghai, China.,Key Laboratory of Nuclear Physics and Ion-Beam Application (MOE), Fudan University, Shanghai, China
| | - Xufei Wang
- Department of Nulcear Science and Technology, Institute of Modern Physics, Fudan University, Shanghai, China.,Key Laboratory of Nuclear Physics and Ion-Beam Application (MOE), Fudan University, Shanghai, China
| | - Wenzhen Xu
- Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, China
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11
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Fuchs H, Padilla‐Cabal F, Zimmermann L, Palmans H, Georg D. MR-guided proton therapy: Impact of magnetic fields on the detector response. Med Phys 2021; 48:2572-2579. [PMID: 33326614 PMCID: PMC8251909 DOI: 10.1002/mp.14660] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 12/03/2020] [Accepted: 12/03/2020] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To investigate the response of detectors for proton dosimetry in the presence of magnetic fields. MATERIAL AND METHODS Four ionization chambers (ICs), two thimble-type and two plane-parallel-type, and a diamond detector were investigated. All detectors were irradiated with homogeneous single-energy-layer fields, using 252.7 MeV proton beams. A Farmer IC was additionally irradiated in the same geometrical configuration, but with a lower nominal energy of 97.4 MeV. The beams were subjected to magnetic field strengths of 0, 0.25, 0.5, 0.75, and 1 T produced by a research dipole magnet placed at the room's isocenter. Detectors were positioned at 2 cm water equivalent depth, with their stem perpendicular to both the magnetic field lines and the proton beam's central axis, in the direction of the Lorentz force. Normality and two sample statistical Student's t tests were performed to assess the influence of the magnetic field on the detectors' responses. RESULTS For all detectors, a small but significant magnetic field-dependent change of their response was found. Observed differences compared to the no magnetic field case ranged from +0.5% to -0.7%. The magnetic field dependence was found to be nonlinear and highest between 0.25 and 0.5 T for 252.7 MeV proton beams. A different variation of the Farmer chamber response with magnetic field strength was observed for irradiations using lower energy (97.4 MeV) protons. The largest magnetic field effects were observed for plane-parallel ionization chambers. CONCLUSION Small magnetic field-dependent changes in the detector response were identified, which should be corrected for dosimetric applications.
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Affiliation(s)
- Hermann Fuchs
- Division of Medical PhysicsDepartment of Radiation OncologyMedical University of Vienna1090ViennaAustria
- Division of Medical PhysicsMedAustron Ion Therapy Center2700Wiener NeustadtAustria
| | - Fatima Padilla‐Cabal
- Division of Medical PhysicsDepartment of Radiation OncologyMedical University of Vienna1090ViennaAustria
| | - Lukas Zimmermann
- Division of Medical PhysicsDepartment of Radiation OncologyMedical University of Vienna1090ViennaAustria
| | - Hugo Palmans
- Division of Medical PhysicsMedAustron Ion Therapy Center2700Wiener NeustadtAustria
- National Physical LaboratoryTW11 0LWTeddingtonUnited Kingdom
| | - Dietmar Georg
- Division of Medical PhysicsDepartment of Radiation OncologyMedical University of Vienna1090ViennaAustria
- Division of Medical PhysicsMedAustron Ion Therapy Center2700Wiener NeustadtAustria
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12
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Fuchs H, Padilla-Cabal F, Hummel A, Georg D. Technical Note: Design and commissioning of a water phantom for proton dosimetry in magnetic fields. Med Phys 2020; 48:505-512. [PMID: 33222211 PMCID: PMC7898880 DOI: 10.1002/mp.14605] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 09/11/2020] [Indexed: 01/03/2023] Open
Abstract
Purpose To design and commission a water phantom suitable for constrained environments and magnetic fields for magnetic resonance (MR)‐guided proton therapy. Methods A phantom was designed, to enable precise, remote controlled detector positioning in water within the constrained environment of a magnet for MR‐guided proton therapy. The phantom consists of a PMMA enclosure whose outer dimensions of 81×40×12.5cm3 were chosen to optimize space usage inside the 13.5‐cm bore gap of the magnet. The moving mechanism is based on a low‐height H‐shaped non‐ferromagnetic belt drive, driven by stepper motors located outside of the magnetic field. The control system and the associated electronics were designed in house, with similar features as available in commercial water phantoms. Reproducibility as well as accuracy of the phantom positioning were tested using a high‐precision Leica AT 402 laser tracker. Laterally integrated depth dose curves and lateral beam profiles at three depths were acquired repeatedly for a 148.2 MeV proton beam in water. Results The phantom was successfully operated with and without applied magnetic fields. For complex movements, a positioning uncertainty within 0.16 mm was found with an absolute accuracy typically below 0.3 mm. Laterally integrated depth dose curves agreed within 0.1 mm with data taken using a commercial water phantom. The lateral beam offset determined from beam profile measurements agreed well with data from Monte Carlo simulations. Conclusion The phantom is optimally suited for detector positioning and dosimetric experiments within constrained environments in high magnetic fields.
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Affiliation(s)
- Hermann Fuchs
- Division of Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna, Währinger Gürtel 18-20, Wien, 1090, Austria
| | - Fatima Padilla-Cabal
- Division of Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna, Währinger Gürtel 18-20, Wien, 1090, Austria
| | - Andreas Hummel
- Division of Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna, Währinger Gürtel 18-20, Wien, 1090, Austria
| | - Dietmar Georg
- Division of Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna, Währinger Gürtel 18-20, Wien, 1090, Austria
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Moreno-Barbosa F, de Celis-Alonso B, Moreno-Barbosa E, Hernández-López JM, Geoghegan T, Ramos-Méndez J. Monte Carlo simulation of the effect of magnetic fields on brachytherapy dose distributions in lung tissue material. PLoS One 2020; 15:e0238704. [PMID: 33035214 PMCID: PMC7546478 DOI: 10.1371/journal.pone.0238704] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 08/20/2020] [Indexed: 12/04/2022] Open
Abstract
The aim of this work was to use TOPAS Monte Carlo simulations to model the effect of magnetic fields on dose distributions in brachytherapy lung treatments, under ideal and clinical conditions. Idealistic studies were modeled consisting of either a monoenergetic electron source of 432 keV, or a polyenergetic electron source using the spectrum of secondary electrons produced by 192Ir gamma-ray irradiation. The electron source was positioned in the center of a homogeneous, lung tissue phantom (ρ = 0.26 g/cm3). Conversely, the clinical study was simulated using the VariSource VS2000 192Ir source in a patient with a lung tumor. Three contoured volumes were considered: the tumor, the planning tumor volume (PTV), and the lung. In all studies, dose distributions were calculated in the presence or absence of a constant magnetic field of 3T. Also, TG-43 parameters were calculated for the VariSource and compared with published data from EGS-brachy (EGSnrc) and PENELOPE. The magnetic field affected the dose distributions in the idealistic studies. For the monoenergetic and poly-energetic studies, the radial distance of the 10% iso-dose line was reduced in the presence of the magnetic field by 64.9% and 24.6%, respectively. For the clinical study, the magnetic field caused differences of 10% on average in the patient dose distributions. Nevertheless, differences in dose-volume histograms were below 2%. Finally, for TG-43 parameters, the dose-rate constant from TOPAS differed by 0.09% ± 0.33% and 0.18% ± 0.33% with respect to EGS-brachy and PENELOPE, respectively. The geometry and anisotropy functions differed within 1.2% ± 1.1%, and within 0.0% ± 0.3%, respectively. The Lorentz forces inside a 3T magnetic resonance machine during 192Ir brachytherapy treatment of the lung are not large enough to affect the tumor dose distributions significantly, as expected. Nevertheless, large local differences were found in the lung tissue. Applications of this effect are therefore limited by the fact that meaningful differences appeared only in regions containing air, which is not abundant inside the human.
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Affiliation(s)
- Fernando Moreno-Barbosa
- Faculty of Mathematical & Physical Sciences, Benemerita Universidad Autonoma de Puebla, Ciudad Universitaria, Mexico City, Mexico
| | - Benito de Celis-Alonso
- Faculty of Mathematical & Physical Sciences, Benemerita Universidad Autonoma de Puebla, Ciudad Universitaria, Mexico City, Mexico
| | - Eduardo Moreno-Barbosa
- Faculty of Mathematical & Physical Sciences, Benemerita Universidad Autonoma de Puebla, Ciudad Universitaria, Mexico City, Mexico
| | - Javier Miguel Hernández-López
- Faculty of Mathematical & Physical Sciences, Benemerita Universidad Autonoma de Puebla, Ciudad Universitaria, Mexico City, Mexico
| | - Theodore Geoghegan
- Department of Radiation Oncology, University of Iowa Hospitals and Clinics, Iowa City, IA, United States of America
| | - José Ramos-Méndez
- Department of Radiation Oncology, University of California San Francisco, San Francisco, CA, United States of America
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De Marzi L, Patriarca A, Scher N, Thariat J, Vidal M. Exploiting the full potential of proton therapy: An update on the specifics and innovations towards spatial or temporal optimisation of dose delivery. Cancer Radiother 2020; 24:691-698. [PMID: 32753235 DOI: 10.1016/j.canrad.2020.06.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 06/07/2020] [Accepted: 06/09/2020] [Indexed: 02/07/2023]
Abstract
Prescription and delivery of protons are somewhat different compared to photons and may influence outcomes (tumour control and toxicity). These differences should be taken into account to fully exploit the clinical potential of proton therapy. Innovations in proton therapy treatment are also required to widen the therapeutic window and determine appropriate populations of patients that would benefit from new treatments. Therefore, strategies are now being developed to reduce side effects to critical normal tissues using alternative treatment configurations and new spatial or temporal-driven optimisation approaches. Indeed, spatiotemporal optimisation (based on flash, proton minibeam radiation therapy or hypofractionated delivery methods) has been gaining some attention in proton therapy as a mean of improving (biological and physical) dose distribution. In this short review, the main differences in planning and delivery between protons and photons, as well as some of the latest developments and methodological issues (in silico modelling) related to providing scientific evidence for these new techniques will be discussed.
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Affiliation(s)
- L De Marzi
- Institut Curie, centre de protonthérapie d'Orsay, campus universitaire, bâtiment 101, 91898 Orsay, France; Université PSL (Paris Sciences & Lettres), 60, rue Mazarine, 75006 Paris, France; Université Paris-Saclay, route de l'Orme-aux-Merisiers, RD 128, 91190 Saint-Aubin, France; Inserm U1021, centre universitaire, bâtiment 110, rue Henri-Becquerel, 91405 Orsay cedex, France; CNRS, UMR 3347, centre universitaire, bâtiment 110, rue Henri-Becquerel, 91405 Orsay cedex, France.
| | - A Patriarca
- Institut Curie, centre de protonthérapie d'Orsay, campus universitaire, bâtiment 101, 91898 Orsay, France; Université PSL (Paris Sciences & Lettres), 60, rue Mazarine, 75006 Paris, France
| | - N Scher
- Institut Curie, centre de protonthérapie d'Orsay, campus universitaire, bâtiment 101, 91898 Orsay, France; Université PSL (Paris Sciences & Lettres), 60, rue Mazarine, 75006 Paris, France
| | - J Thariat
- Service de radiothérapie oncologique, centre François-Baclesse, 3, avenue General-Harris, 14000 Caen, France; Laboratoire de physique corpusculaire de Caen, 6, boulevard du Maréchal-Juin, 14050 Caen cedex, France; Institut national de physique nucléaire et physique des particules (IN2P3), 6, boulevard du Maréchal-Juin, 14050 Caen cedex, France; EnsiCaen, 6, boulevard du Maréchal-Juin, 14050 Caen cedex, France; CNRS, UMR6534, 6, boulevard du Maréchal-Juin, 14050 Caen cedex, France; Unicaen, 6, boulevard du Maréchal-Juin, 14050 Caen cedex, France; Normandie Université, 6, boulevard du Maréchal-Juin, 14050 Caen cedex, France
| | - M Vidal
- Centre Antoine-Lacassagne, 33, avenue Valombrose, 06000 Nice, France
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